1. Technical Field
The present invention relates to a length measuring instrument.
2. Background Information
Such length measuring instruments are known as encapsulated length measuring instruments, and they serve to measure the position of two objects that are displaceable relative to one another. Encapsulated length measuring instruments are used especially in machining machines for measuring the relative motion of a tool relative to a workpiece that is to be machined.
Such length measuring instruments are described in European Patent Disclosure 0 418 212 A2 and U.S. Pat. No. 4,340,814, for example. Each of the length measuring instruments include a U-shaped hollow profile section with two legs extending parallel to one another, a base, and a slot-like opening facing the base and extending in the longitudinal direction. This opening is covered by sealing elements. Both a scale and a scanning unit are disposed inside the hollow profile section, and for position measurement, the scanning unit can be displaced in the longitudinal direction relative to the scale. The scanning unit has a sword-shaped driver extending through the sealing lips to the outside. The face ends of the hollow profile section are each closed with an end piece, which is also embodied for mounting the hollow profile section on one of the objects to be measured. The end piece has an insertion region, with which it plunges into the inside of the opening in the hollow profile section. In the length measuring instruments of the prior art, the connection between the hollow profile section and the end piece is made by screwing or pinning the lateral legs of the U-shaped hollow profile section to the insertion region.